Are these cups supposed to be used on a 1969 C10 or did the previous owner use them from another vehicle? I have searched and have not been able to find pictures of them on a C10, that is why I am questioning the situation.

I would like that thank poster "In The Ten Ring" for posting a pic of cab supports in an older thread. I did not realize the front mounts were a different thickness from the rear. Saved me from messing myself up! Huge help so thank you Sir! This site is invaluable.

Here's a picture of the frame mount. I ordered new ones from LMC. Should be here later in the week. Also a picture of the cab removed from the frame. I have some patching to do and thanks to some of the threads here I am confident I can make it happen.
Also a picture of the truck before I started this project. I pulled the 6 cyl and power glide and am putting a SBC in it with a yet to be determined transmission.
Last Picture is of my other vehicle. Need to finish this truck so I can get my car back in my garage!